Piston expander



PISTON EXPANDER Filed June 14, 1944 FIGQ.

INVENTOR DALLAS MSM/T v ATTORNEYS Patented Aug. 7, 1945 UNITED STATES PArENT-T OFFICE I 'lj'allas M: Smith, Kirkwoodi Mo., assignor to 'McQuay-Norris Manufacturing Company, St. Louis, Mo., acorporation of Delaware Y Applicationijune 14, 1944. serial-fie. 540,253

- 7 Claims. (o1. 309-12) I This invention relates generally to piston expanders and particularly to such an expander as maybe inserted in the piston under treatment without the necessity of removingthe wrist pin. -.Heretofore,.piston expanders have-been provided in avariety of forms which, for the'most part, necessitated the removalof the wrist pin in order to position the expander within the piston. Atype of piston expander which has been used to a substantialextent, however, and which does notrequire removal of the wrist pin in order to position the expander within thepiston, involves the driving of an element into wedging engagementtbetween the sides of the wrist pin bosses and the interiorof the thrust face of the piston; The use of such an expander as that last referred to results 'i'nth setting up of tremendous strains between the wrist pin boss and the p'ortionsof the skirt thereadiacent with the consequence that not infrequently fractures occurinthatregion."

" Th object of the present invention, lgenerally stated, is to provide a piston expander of the character which is insertable without removal of the wristpin and which does not," in operation, transmit thrust tothe wrist pin boss. l

Other objects will become" apparent to those skilled in the art when the following description is read in connection with'th'e i accompanying drawingg'inwhichz' 1 X Figural is a perspective view of an expander. constructed in accordance with oneembodiment of the pres'ent'inven'tion;

Fig; 2 is a sectional view of aipiston showing the expander of Figfi'l" in position therein;

Fig. 3 is'adetailed view'showing the anchorage providedon the expander of Figs. 1- and 2 for holding the expander in position Fig. '4 is a view inside elevationof an expander constructed in accordance with'another embodiment of the present invention;

Fig.. 5 is a plan view of the expander shown inFig.4;' I

Fig. 6 is" a' sectional view taken along lines 66 ofFi 5; r r a Fig. 7 is a fragmentary view corresponding, in part, to Fig. 2 and showing the expander of Figs. 4 to 6, inclusive, iii position in a'piston;

Fig. 8 is aview inSsideeleVatio'n of a further,

modification; and v I l Fig. 9 isaview inside elevation of a modification of the form shown in Figs. .1 and 2.

In accordance with the presentinvention, gen erallystated, a piston;expander is formed of a generally oval shape having portions adjacent the .ends of its major axis for engaging the interior thrust faces of-a piston. Between the portions which engage the interior of a'piston connecting portions are provided which'are cut away in order to accommodate thev wrist pin bossessuflicient material, however, remaining below the cutaway recess to transmit the expanding forces chordally across the piston from one thrust face to the other without requiring that the wrist pin bosses receive the reaction of the expanding forces. i

The present invention further contemplates that-such a piston expander be anchored in position by the provision thereon of yieldable projections, which may be slightly distorted in the process of inserting theexpander within the piston but which, when they have passed obstructions existing in the piston structure-expand to prevent removal of the expander therefrom. For example, such projections may be provided in a'form which will enter a horizontal slot or a horizontally'slotte'd piston, ormay be provided in a form which will engage overanother interior projection'of the piston such as thewrist pin boss or interior ribbing; it being noted in this connection, however, that when the engagement is with the wrist pin boss, the expanding thrust is not su'stainedthereby but merely the forces of inertia which tend to dislodge the expander from position.

' Referring now to Figs. 1, 2, and 3 of the drawing for one illustrative embodiment of the present invention, the expander is composed of a band of metal [formed to an oval configuration as shown,so asto provide substantially largebearing faces 2and 3 adapted to engage the interior of the thrust faces of the piston. Between the bearing faces 2 and 3 of the expander are connecting portions 4 and 5 which are cut away, as shown clearly in Fig. 1, to provide a U-shaped recess of size sufficient to accommodate the wrist pin boss and prevent the expanding forces from being sustained by'the wrist pin boss. Inthe embodiment shown in Fig. 1' the expander is formed of asingl strip of metal cut out as shown and welded together at 6. r l In order to anchor the expander within the piston a. resilient tongue I having'a turned. over lip 8 is provided in one or both of the bearing surfaces 2' and 3. The tongue I is sufficiently.

flexible thatit will yield inwardly, as shown in the dotted line position in Fig. 3, to an extent suficient that the outer edge of the lip 8 will move upwardlyalong the inside wallof the piston untilthe horizontalslot 9 of th piston shown rangement of interlocking tongues as shown at;

H in Fig. 9 may be provided. This arrangement has the virtue of permitting the ends to be sep-" arated in order to place the expander over the slender portion of a connecting rod; whereas in the case of the embodiment shown-in Fig.- l,

where the ends are permanently connected, it is sometimes impossible to pass'the expander over the connecting rod bearing.

In'the embodiments shownin Figs. 4 to 7, is

elusive, the expander is in general identical with that previously described, being provided with bearing surfaces .2 and '3 andconnecting'portions 5 and 6 each having cutouts to accommodateand clear the wrist pin boss; but in lieu of the anchor age means shown in theprevious embodiment the present embodiment is provided with fingers" l2, of which in the embodiment" shown thereare four, but one will frequently suffice. The fingers l2 are inclined in two directions',-as clearly shown" in Figs. 5 and 6, so as to be cammed inwardly whenthe expander is inserted from the bottom of the'piston past the wrist'pir1boss.- When'in the'process of insertion the fingers 12 havecleared the boss I they spring outwardlyfand,

being then disposed as shown in Fig; '7 above and within the horizontal'diameter of the boss, se-

curely anchor the expander in position-so that it can-not bedisplaced by theforces of inertia.

In the embodiment shown :in Fig.= 8 a further example of anchorage means is disclosed." In this instance a latch piece [3 is pivoted at H to that portion of the expander which will extend above the wrist pin boss. The length and configuration of the latch bar I3-is so designed thatthe same will'not interfere with movement of. the expander into proper position within the:pis.- ton. This, however, does not require that'the' latch bar l3" assume an upright positionuntil the expander reaches its ultimate positiorrwithin the piston. on the contrary; after the upper end of the latch bar l3 has assedbeyond the hori-. zontal diameter of the wrist pin' boss, thelatch bar may begin to be-swung in a counterclockwise direction about its pivot so asito 'clear .the interior head of thepiston and finally. assume a position'whereat it will-extend across the top of. the pin boss or other projection on the interior. of the piston and be arranged forengagement with a suitable latch lug l for holding .the latch bar H! in anchoring position, which would be substantially'horizontal as shown in Fig; 8. From the foregoing description those skilled in the art will readily understand the construction and operation of the expander as shown herein and appreciate thatethe expander, while readily insertable without removalof the wrist pin, may nevertheless be securely located within the piston without-necessitating the setting up of thrusts the reaction o'f which must be taken by the pin boss.

While several forms of anchorage means have been shown in the accompanying drawing, it is to be distinctly understood that thepresent'invention is not limited to the details of the'forms ZJA'piston expander comprising, a generally oval body havingportions at the ends of its v{major-axis for engaging the interior surface of pistoniaces, connecting portions therebetween,

a U-shaped cutout Open at the upper edge in each of said connecting portions to accommodate theprojections on the interior of the piston, and means for anchoring the body within the pistonv 1 3. A' piston' ex'pander comprising, agenerall-y oval body having portions at the ends'of its major axis for engaging the: interior surface cf-z lston faceaconnecting portions therebetween, aU- shaped cutoutopen at'the upper edge in each of 'said connecting! portions to accommodate the projections on'the interior of thepiston', andresilient means'on the: body foranchoring engage ment with aninteriorfixed part 'ofa piston..

4. A piston expander comprisingya generally oval body having portions at the ends of its major axis 'for engaging'the interiorisurface =01 piston faces, connecting portions therebetween; a U- shaped cutout open "at the upper edge in each.

of said connecting'portions to accommodate the projections on'the interior of'the piston and lugs on the body positioned to encounter obstructions on the interior-ofthe piston while being insei'ted; said'lugs being arranged to yield to pass-such obstructions and to resume normal positionrbeyond such-obstructions thereby to anchor 'the body'within'the pistom-n i 5. A piston: expander. comprising, a generally oval body having portio'n'sat the ends-of its major axis for engaging the interior-surface of piston faces; substantially chordal -connecting portions, a U-shaped "cutout open at the upper edge in each-of said connectingportions to clear the bosses of the piston, and'ai lug adapted to clear the .boss duringvinsertion but to anchor above the boss when. completely inserted.

6. A piston expandercomprising agenerally oval body having portions at the ends of its major axis for engaging 'the:interior"surface of piston faces, substantially chordal' connecting: portions, a U-shaped cutout open at the upper edge in each of said connecting portions toclearthe bossesof the piston, and a-lug arranged to enter the slot of the piston when the-bodyis completely inserted therein. I

7.. A piston expander comprising a generally oval body having portions at the ends of its major axis for engaging the "interior" surface of piston faces, substantially chordal connecting: portions; a U-sha'ped cutout open at the"u'pper edge-in each of said connecting portions to clearthe bosses of the piston, and a movable latch member connected withth'e' body atone sideof them;- out and arranged for interlocking engagement with the bodyatthe othersideo'f'the cutout,said latch whenengaged extending crosswise of the piston above the boss. 

